On Mon, 2012-06-25 at 18:55 -0400, Kevin O'Connor wrote:
On Wed, Jun 20, 2012 at 10:25:13AM +0100, Ian Campbell wrote:
On Wed, 2012-06-20 at 10:22 +0100, Ian Campbell wrote:
Subject: [PATCH] enable Xen support by default.
In this context I thought it would also be useful to make CONFIG_DEBUG_IO_PORT dynamic. However with the below I get lots of build errors about xen_cpuid_base not being defined. I got similar errors without the VAR16VISIBLE and GET_GLOBAL hunks. I suspect this is due to the variable being used in both 32 and 16 bit mode and my not knowing what I'm doing in that regard ;-)
xen_cpuid_base is defined in xen.c which is only compiled in 32bit mode, so you can't declare a variable as VAR16VISIBLE there.
Ah, right yes, thanks! I think I keep tripping over that...
I wonder if it is simpler to define a "u16 DebugOutputPort VAR16VISIBLE = CONFIG_DEBUG_IO_PORT" in output.c and then override it early in the xen boot sequence though.
Yes, this makes sense. I actually went one further and nuked the Kconfig option, since it's only real non-default use was Xen. So now I makde it default to 0x402 and set it to 0xe9 in the Xen case.
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From 903d84d2c320543ac07ae1298d57643575d6ffc8 Mon Sep 17 00:00:00 2001
From: Ian Campbell ian.campbell@citrix.com Date: Wed, 27 Jun 2012 11:39:01 +0100 Subject: [PATCH] Xen: Autodetect debug I/O port at runtime instead of via Kconfig
This allows a common image which supports Xen to still print debug
Signed-off-by: Ian Campbell ian.campbell@citrix.com --- src/Kconfig | 7 ------- src/output.c | 4 +++- src/util.h | 1 + src/xen.c | 5 +++++ 4 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/src/Kconfig b/src/Kconfig index 8120ff7..8932c9e 100644 --- a/src/Kconfig +++ b/src/Kconfig @@ -361,11 +361,4 @@ menu "Debugging" information by outputing strings in a special port present in the IO space.
- config DEBUG_IO_PORT - depends on DEBUG_IO - hex "Debug IO port address" - default 0x0402 - help - Bochs uses the 0x0402 address by default, whereas Xen - makes the 0xe9 IO address available for guests use. endmenu diff --git a/src/output.c b/src/output.c index 37c4942..25300d0 100644 --- a/src/output.c +++ b/src/output.c @@ -23,6 +23,8 @@ struct putcinfo {
#define DEBUG_TIMEOUT 100000
+u16 DebugOutputPort VAR16VISIBLE = 0x402; + void debug_serial_setup(void) { @@ -77,7 +79,7 @@ putc_debug(struct putcinfo *action, char c) return; if (CONFIG_DEBUG_IO) // Send character to debug port. - outb(c, CONFIG_DEBUG_IO_PORT); + outb(c, DebugOutputPort); if (c == '\n') debug_serial('\r'); debug_serial(c); diff --git a/src/util.h b/src/util.h index dbee0e5..ef8ec7c 100644 --- a/src/util.h +++ b/src/util.h @@ -231,6 +231,7 @@ int wait_preempt(void); void check_preempt(void);
// output.c +extern u16 DebugOutputPort; void debug_serial_setup(void); void panic(const char *fmt, ...) __attribute__ ((format (printf, 1, 2))) __noreturn; diff --git a/src/xen.c b/src/xen.c index 961e316..128e6c0 100644 --- a/src/xen.c +++ b/src/xen.c @@ -64,6 +64,9 @@ void xen_probe(void) dprintf(1, "Found hypervisor signature "%s" at %x\n", signature, base); if (strcmp(signature, "XenVMMXenVMM") == 0) { + /* Set debug_io_port first, so the following messages work. */ + DebugOutputPort = 0xe9; + dprintf(1, "Found Xen hypervisor signature at %x\n", base); if ((eax - base) < 2) panic("Insufficient Xen cpuid leaves. eax=%x at base %x\n", eax, base); @@ -71,6 +74,8 @@ void xen_probe(void) break; } } + if (!xen_cpuid_base) + dprintf(1, "No Xen hypervisor found.\n"); }
static int hypercall_xen_version( int cmd, void *arg)